This application claims the benefit of Korean Patent Application No. 1999-23168, filed on Jun. 21, 1999, under 35 U.S.C. xc2xa7119, the entirety of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a liquid crystal display device having a digitizer.
2. Description of Related Art
Liquid crystal display (LCD) panels are used in many electronic data handling devices, including lap-top computers, personal digital assistants, personal organizers, and point-of-sale terminals. Some display systems include the ability of inputting information directly onto the display screen by pointing or writing with a finger or a stylus. For example, a finger may be used to push a xe2x80x9csoftxe2x80x9d button that is displayed on the screen, or a stylus can be used to sign one""s name and have it captured and displayed electronically.
An LCD panel, shown in FIG. 1, comprises a liquid crystal display (LCD) module xe2x80x9cLxe2x80x9d and a digitizer xe2x80x9cDxe2x80x9d. The LCD module xe2x80x9cLxe2x80x9d has lower and upper substrates 10 and 20 with an interposed liquid crystal layer 13. The lower substrate 10 has switching elements (not shown), such as thin film transistors (TFTs), and the upper substrate 20 has a common electrode, a color filter and a black matrix. A linear polarizer 22 is located on the upper substrate. The lower and upper substrates 10 and 20 are sealed by a sealant 12 to prevent leakage of the liquid crystal. Further, pads (not shown) patterned on the lower substrate 10 are electrically coupled to a printed circuit board (PCB) 14 through a TCP (tape carrier package) 17 having a film 18 carrying a drive integrated circuit (IC) 19. Pads (not shown) on the lower substrate 10 and output signal lines of the film 18 are electrically connected with an anisotropic conductive film 16a, and signal lines of the PCB 14 and input lines of the filml8 are electrically connected with an anisotropic conductive film 16b. 
Furthermore, the digitizer xe2x80x9cDxe2x80x9d is a location-sensing component having first and second plates 24 and 26, and a drive circuit 25 (see FIG. 4). The plates 24 and 26 serve to produce or detect signals indicative of the location of a stylus, a finger, or another input device. Each of the plates 24 and 26 has a substrate, a transparent electrode, and a metal pattern layer that are stacked in that order. Further, as shown in FIG. 2, which is a plan view of the first plate 24 of the digitizer xe2x80x9cDxe2x80x9d, the first plate 24 has a plurality of regularly spaced digitizer electrodes 28 formed along the edges of an active region 32. The digitizer electrodes 28 are connected to an external digitizer drive circuit (not shown). The active region 32 is a location sensing region having a resistive layer in the form of a strip or a grid.
Further, the drive circuit 15 for the LCD module xe2x80x9cLxe2x80x9d shown in FIG. 3 comprises a power supply 15a for supplying a voltage, a clock generator 15b for producing clock signals to drive the LCD device, a gamma circuit 15c for collecting a gamma characteristic of the LCD device, a controller 15d for controlling all components of the LCD module xe2x80x9cLxe2x80x9d, and data and gate drivers 15e and 15f for producing images. Further, the drive circuit 25 for the digitizer xe2x80x9cDxe2x80x9d shown in FIG. 4 comprises a power supply 25a for supplying a voltage, a clock generator 25b for producing clock signals to drive the digitizer, a controller 25c for controlling all components of the digitizer xe2x80x9cDxe2x80x9d, an analog to digital (A/D) converter 25d for converting analog signals to digital signals, an input/output (I/O) unit 125e for conveying analog signals from the digitizer to the A/D converter 25f and conveying signals from the controller 25d to the digitizer, and an input/output (I/O) unit 225f for transferring digital signals in the form of x and y coordinate values from the AID converter 25d to a main system of the device having the LCD device such as notebook computer by the controller 25c. 
However, the LCD panel described above has disadvantages. First, as shown in FIG. 2, since a plurality of wires 30 are directed along one direction for connection with the external drive circuit 25, the wires 30 differ in length, thereby causing different RC delays. Second, as shown in FIGS. 3 and 4, the digitizer xe2x80x9cDxe2x80x9d and the liquid crystal display module xe2x80x9cLxe2x80x9d use different drive circuits 15 and 25 even though they have some similar elements, such as a power supply, a controller and a clock generator. Multiple similar elements increase the production cost of an LCD device with a digitizer. Furthermore, multiple similar elements make it difficult to achieve a compact LCD panel.
To overcome the problems described above, preferred embodiments of the present invention provide a liquid crystal display (LCD) device having a digitizer in which the drive circuit for the digitizer is integrated with the drive circuit for the LCD device.
Another object of the present invention is to provide a compact LCD device.
Another object of the present invention is to provide a low cost LCD device.
To achieve the above objects, the present invention provides a liquid crystal display device having a digitizer, including: a first frame; a liquid crystal panel supported by the first frame, the liquid crystal panel having a display region and a side wall portion; a digitizer located on the liquid crystal panel, the digitizer having a peripheral portion; and a second frame having a front surface with an opening region and a side wall portion, the front surface pressurizing the peripheral portion of the digitizer, and the opening region formed at a location corresponding to the display region of the liquid crystal panel.
The liquid crystal display device of the present invention further includes a printed circuit board having a drive circuit for driving the digitizer; and a first connection electrically connecting the printed circuit board with the digitizer, with the first connection passing between the side wall portion of the liquid crystal panel and the side wall portion of the second frame.
The liquid crystal display device further includes a printed circuit board located on a back surface of the first frame, the printed circuit board having a controlling circuit for controlling both the liquid crystal panel and the digitizer.
The digitizer includes a plurality of digitizer electrodes covered by the front surface.
The present invention also provides a liquid crystal display device used by a main system, including: a digitizer for producing signals indicative of the location of an external input and driven according to a first clock generated by a first clock generator; a liquid crystal display device for displaying predetermined information according to signals from the digitizer, the liquid crystal display device having first and second substrates with an interposed liquid crystal layer, and data and gate lines; and a printed circuit board having a controlling circuit for controlling the digitizer and the liquid crystal display.
The drive circuit includes a power supply for supplying a voltage to the LCD panel and the digitizer; a clock generator for producing clock signals to drive the LCD device and the digitizer; an analog to digital (A/D) converter for converting analog signals to digital signals; a gamma circuit for correcting gamma characteristics of the LCD device; a first input/output (I/O) unit for conveying analog signals to the A/D converter and conveying signals from the controller to the digitizer; a second input/output (I/O) unit for transferring digital signals in the form of x-y coordinate values from the AID converter to the main system; data and gate drivers driven by the clock generator; and a controller for controlling all components of the drive circuit.
The first I/O unit is beneficially a serial port, a parallel port, a universal serial bus (USB), or an IEEE 1394 bus.
The digitizer includes a) a first digitizer substrate having a rectangular shape over the tipper substrate of the liquid crystal display device; b) a second digitizer substrate having a rectangular shape over the first digitizer substrate; c) a protective layer on the second digitizer substrate, d) a first pair of digitizer electrodes disposed parallel to each other and along opposite edges of the first digitizer substrate; d) a second pair of digitizer electrodes disposed parallel to each other and along opposite edges of the second digitizer substrate, the second pair of digitizer electrodes being perpendicular to the first pair of digitizer electrodes, e) first and second drive circuit boards for driving the first and second pairs of digitizer electrodes, each drive board disposed along neighbering edges of the first and second transparent conductive layers, and f) electric connections for connecting the first and second drive circuit boards to a corresponding pair of digitizer electrodes, with the electric connections having the same length.